MARINE ECOLOGY PROGRESS SERIESMar Ecol Prog Ser

Vol. 397: 269–278, 2009doi: 10.3354/meps08396

Published December 17

INTRODUCTION

Species in the genera Corallium and Paracorallium(Subclass Octocorallia; Order Alcyonacea; FamilyCoralliidae) have long been known as precious coralsbecause of the use of their skeletons for ornament,medicine and other valuable products. For many thou-sands of years, precious corals have been collectedfrom the Mediterranean and have attracted the inter-est of mankind worldwide (Grigg 1975). In Japan, theprecious coral fishery began in Kochi during the 19thcentury (Kosuge 1993), and continues to the presentday in the areas of Kochi, Kagoshima and the RyukyuArchipelago. It is generally believed that the biomassof precious corals has decreased because of collecting,but until now, no data from commercial harvestinghave been published. There is not yet enough dataavailable to estimate the abundance of precious coralsremaining. Our goal here is to begin addressing this

deficit by reporting recent data provided to us by alocal harvesting company. We undertake this work tobegin efforts for management and conservation of theprecious coral resource.

The first mention in the scientific literature of aJapanese precious coral was by Ridley (1882, p. 229),who described a colony ‘said to come from Japan’ andwhich he tentatively identified as Pleurocoralliumsecundum var. elatior. Kishinouye made the first stud-ies in Japan of Japanese precious corals (Kishinouye1902, 1903a,b, 1904a,b), investigating aspects of theiranatomy, chemistry, morphology, reproduction, sym-bioses and taxonomy. His work is the only taxonomicwork ever undertaken on the group since Ridley’s firstmention. He gave species rank to Ridley’s variety,naming it Corallium elatius, and named 6 new speciesfrom Japanese waters, C. boshuensis, C. japonicum, C.inutile, C. konojoi, C. pusillum and C. sulcatum. Over50 yr later, Bayer (1956) described new species of

© Inter-Research 2009 · www.int-res.com*Email: m_nonaka@kaiyouhaku.or.jp

Recent harvest records of commercially valuableprecious corals in the Ryukyu Archipelago

Masanori Nonaka1,*, Katherine Muzik2

1Okinawa Churaumi Aquarium, 424 Ishikawa Motobu-Cho, Okinawa 905-0206, Japan2Japan Underwater Films, 617 Yamazato, Motobu-Cho, Okinawa 905-0219, Japan

ABSTRACT: Data, including depth, temperature and substrate, are reported for 143 colonies of 3 spe-cies of precious corals (Subclass Octocorallia; Family Coralliidae) collected in the Ryukyu Archipel-ago from June 2005 to May 2008. Colonies were collected by a commercial harvesting company usinga remotely-operated vehicle (ROV) and a manned submersible, and identified tentatively as Para-corallium japonicum, Corallium elatius and Corallium konojoi. The data suggest that these specieslive deeper in lower latitudes (Amami, Okinawa and Ishigaki regions) than in higher latitudes (south-ern Kagoshima). Colonies of C. elatius may be larger at lower latitudes than at higher latitudes, butwith the data available so far this cannot be definitely determined. Size differences may reflect har-vest history, not physical or biological factors. (The more southern regions have been exploited morerecently than the northern region.) There has not yet been enough data made available to estimatethe resource of precious corals remaining in the Ryukyu Archipelago. More studies of their taxonomyand biology, especially growth rates, age and size at fertility and timing of reproduction, and data onbiomass are necessary in order to make meaningful estimates.

KEY WORDS: Precious corals · Coralliidae · Commercial harvest records · Ryukyu Archipelago ·Submersible/ROV harvest

Resale or republication not permitted without written consent of the publisher

OPENPEN ACCESSCCESS

Contribution to the Theme Section ‘Conservation and management of deep-sea corals and coral reefs’

Mar Ecol Prog Ser 397: 269–278, 2009

Corallium from Hawaiian waters, and provided in thesame publication a taxonomic key to all species knownat the time, including thoses from Japan.

According to Grigg (1975), colonies tentatively iden-tified as Corallium elatius and C. konojoi were seizedfrom a Japanese fishing boat off the coast of Palau in1973. Pasternak (1981) recorded C. boshuensis in theMarcus-Necker Sea Mounts near Hawaii. Grigg (1984)reported the distribution by latitude and depth of 3commercial species in Japan, including: C. japonicumfrom mainland Japan, Okinawa, and the Bonin Islandsand C. konojoi and C. elatius from Japan to the Philip-pines. (The Japanese species known as C. japonicum isnow known as a species of Paracorallium, being movedto this new genus by Bayer & Cairns in 2003.) Harper(1988) reported on the distribution of precious corals inthe South Pacific region, listing C. konojoi and C.elatius from the Solomon Islands, Paracorallium inutilefrom Tonga and P. japonicum from Vanuatu. Imahara(1996) listed all octocorals ever described from Japan-ese waters, including species of Corallium. With theexception of Kishinouye’s work over 100 yr ago, mostof these reports on Japanese precious corals were verybrief, with identifications often tentative.

Studies of the biology and ecology of Japanese pre-cious corals remain scarce. Basic information of theirnatural history, such as how much thesecorals grow on an annual basis, age atreproduction and even time of spawning,are not yet known. There is just onereport (Grigg 1974) giving growth ratesof Japanese corals. In a personal commu-nication to Grigg from U. Kurata, growthrates of up to 0.3 cm yr–1 in length werereported for tagged specimens of Para-corallium japonicum. Recent studies inJapan (Ueno et al. 1993, Ueno & Tashima1998, Iwase 1995, Nonaka et al. 2006,Reimer et al. 2008) have focused only onthe biology of Japanese precious corals incaptivity.

MATERIALS AND METHODS

Sampling. Colonies were collectedfrom the Ryukyu Archipelago, the south-ernmost region of Japan (Fig. 1). In thenorthern (southern Kagoshima) andAmami regions of the Ryukyu Archipel-ago, corals were collected by mannedsubmersible at depths of 115 to 300 m(Appendix 1). In the southern regions(Okinawa and Ishigaki), corals were col-lected by remotely operated vehicle

(ROV) from depths of 194 to 319 m (Appendix 1). Thesamples were selectively harvested for commercialuse, with larger colonies more likely to be collectedand colonies under certain sizes avoided. Data (waterdepth, temperature, type of substratum and latitude)were recorded for the immediate area of the samplecollected. From 4 June 2005 to 1 March 2006, weobtained 83 samples, and from 23 June 2007 to 27 May2008, an additional 60 samples (Appendix 1). To pro-tect the resource, and to keep the agreement madewith the harvesting company for this research, onlyapproximate latitudes and no longitudes of the collect-ing locations are revealed in this report. It was alsoagreed not to report specifications of the ROV and sub-mersible used for collection. Photographs were firstmade of colonies in situ (Fig. 2A); once collected,colonies were photographed with a scale, on-boardship (Fig. 2B). In situ photographs were approximately300 000 pixels (640 × 480) and on-board photographswere 8 million (3264 × 2448) pixels. Photographs takenby observers inside the submersible and on-board thesubmersible support vessel were approximately 6 mil-lion pixels (3072 × 2048). Colony height, width andmain stem diameters were calculated by the authorsfrom the digital photographs provided to them by thecompany, using the scales included in the photos

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Fig. 1. Regions of collection of Paracorallium japonicum, Corallium elatiusand C. konojoi in the Ryukyu Archipelago, Japan, during 2005–2006

and 2007–2008

Nonaka & Muzik: Harvest records of precious corals

(Fig. 2B). Colony width is the maximum spread of thecolony. Colony height is the maximum height mea-sured perpendicular to the maximum width. Data ondensities and biomass were not available. Terminaltwigs up to 8 cm long of each colony sampled werepreserved in 99.5% ethanol and provided by the com-pany to the authors for study (99.5% ethanol is recom-mended for future DNA studies). All samples are beingkept in the collection of the Okinawa ChuraumiAquarium.

Identifications. Colonies were identified using ac-cepted morphological characters, such as color, branch-ing pattern, color of axial skeleton and coenenchyme,polyp arrangement, polyp size, and sclerite shape, sizeand color. Polyp details were observed and measuredby light-microscope. Sclerites were separated from thesoft tissue of the coenenchyme by treatment with 5%hypochlorite (ordinary household bleach) and rinsedwith tapwater to prepare for scanning electron pho-tographs. Sizes and shapes of sclerites were examinedand recorded by using a scanning electronic micro-scope model Keyence VE-8800. Identifications followKishinouye (1903a, 1904a), Bayer (1956), Bayer &Cairns (2003) and Nonaka & Muzik (in press). In Japan,there are 7 species recognized in the Family Coralli-idae, 6 described by Kishinouye (Kishinouye 1902,

1903a, 1904a,b) and one species by Ridley (1882). Forthe present study, only the 3 species which have com-mercial value, Paracorallium japonicum (Kishinouye,1903), Corallium elatius (Ridley, 1882), and Coralliumkonojoi Kishinouye, 1903, were examined.

Analysis of biological and environmental data. Weexamined the following relationships for each species:(1) width frequencies; (2) distribution and colonywidth; (3) colony width and colony height; (4) colonywidth and main stem diameter; and (5) depth and lati-tude of collection site. Broken colonies were excludedfrom analyses requiring colony measurements. Statisti-cal analysis was performed using Statistica. Watertemperature data were collected with each sample andare reported in Appendix 1. Water temperatures forROV-sampled colonies were taken with a quartz tem-perature sensor and for submersible-sampled colonieswith a mixed-liquid thermometer. Reports from bothsensors were accurate to 1°C.

RESULTS

Species sampled

Samples were collected from approximately 100 to300 m deep offshore the islands of Ishigaki, Okinawaand Amami, and the small islands offshore southernKagoshima (Fig. 1, Appendix 1). All colonies report-edly inhabited hard rock substratum. Of the 165colonies collected, 143 were commercially valuablespecies and are discussed here. Seventy-eight coloniesappeared to be Paracorallium japonicum, 46 Coralliumelatius and 19 C. konojoi. Colonies of C. konojoi werefound mostly in northern areas, but the other 2 specieswere present throughout the study area.

Width frequencies

Width frequencies are shown in Fig. 3. Colonies ofParacorallium japonicum were the smallest of the spe-cies sampled. Average (±SD) colony width was 37.9 ±10.48 cm, with a mode ranging from 35 to 40 cm wide,a maximum colony width of 64 cm and a minimumwidth of 18 cm. For Corallium konojoi, the averagecolony width was 39.4 ± 12.11 cm, with a mode rangingfrom 40 to 45 cm, a maximum colony width of 55 cm,and a minimum width of 16.5 cm. The largest colonieswere of C. elatius, with an average colony width of 64.2± 27.76 cm, a maximum width of 157 cm, and a mini-mum width 25.0 cm, although the mode, 45 to 55 cm,was much smaller. Of all C. elatius colonies collected,35% were over 75 cm wide (Fig. 3). Colony widthswere significantly different among the 3 species

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Fig. 2. Corallium elatius. (A) Colony in situ being harvestedby ROV. (B) Same colony on-board harvest company vessel,

with scale

Mar Ecol Prog Ser 397: 269–278, 2009

(ANOVA, p < 0.01). Colonies of C. elatius were signifi-cantly wider than the other 2 species (Tukey’s HSDtest, p < 0.01).

Relationships between distribution and colony width

We collected more colonies of Paracorallium japon-icum from near Okinawa than from the northern(southern Kagoshima) and southern regions (near Ishi-gaki) (Fig. 4), but found no relationship between distri-bution and colony width in our samples (Fig. 5). Wefound comparatively wider colonies of Coralliumelatius in southern regions, although the largest colony(157 cm wide) was collected from the northern region(Fig. 5). Insufficient samples of C. konojoi were col-lected to permit drawing any conclusions about distri-bution by width.

Relationships between (1) colonywidth and height and (2) colony width

and main stem diameter

Colony width was plotted againstcolony height for each of the 3 species(Fig. 6A). Of the 143 colonies collected,86 (61%) were collected intact andwere measured to provide this data.Fifty-one specimens were identified asParacorallium japonicum, 24 as Coral-lium elatius and 11 as C. konojoi. A sig-nificant relationship was found be-tween width and height only for C.elatius (Fig. 6A). The correlation analy-sis for C. elatius yielded the equationy = 15.976 + 0.36205x, with r2 = 0.75.The equations yielded for P. japonicum,y = 12.367 + 0.33073x (r2 = 0.51); and for

C. konojoi, y = 4.7942 + 0.56662x (r2 = 0.55), were notsignificant and the data are not shown.

Colony width was also plotted against diameter of themain stem for each of the 3 species. Again, only forCorallium elatius was there a significant correlation.Correlation analysis yielded the equation y = 36.662 +4.1484x (r2 = 0.79; Fig. 6B). In Paracorallium japonicum (y= 32.649 + 2.1434x, r2 = 0.35) and C. konojoi (y = 41.379 +0.92258x, r2 = 0.31) there appeared to be no correlationbetween colony width and diameter of the main stem.

Water temperatures at sampling sites

Temperatures at sampling sites ranged from 14 to22°C and are reported in Fig. 7 and Appendix 1. Differ-ences in temperature at each depth were less than 5°Cthroughout the year in the Ishigaki and Kagoshima

272

0

2

4

6

8

10

12

14

16

18

20

Num

ber

of c

olon

ies

20 40 60 80 100 120 140 16030 50 70 90 110 130 150

Colony width (cm)

P. japonicum

C. elatius

C. konojoi

Fig. 3. Paracorallium japonicum, Corallium elatius and C. konojoi. Widthfrequency distribution of collected colonies

Latitude (°N)24 26 28 30

P. japonicum

C. elatius

C. konojoi

Num

ber

of c

olon

ies

5

10

15

20

25

30

0

Ishigaki Okinawa S Kagoshima Amami

0

40

80

120

160

24 26 28 30 32Latitude (°N)

Co

lony

wid

th (c

m)

P. japonicum

C. elatius

C. konojoi

Ishigaki Okinawa Amami S Kagoshima

Fig. 4. Paracorallium japonicum, Corallium elatius andC. konojoi. Relationship between latitude and number ofcolonies for each species sampled during 2005–2006

and 2007–2008

Fig. 5. Paracorallium japonicum, Corallium elatius andC. konojoi. Relationship between latitude and colony width

for each species collected

Nonaka & Muzik: Harvest records of precious corals

regions (Fig. 8). Only wintertime temperatures wereavailable for the Okinawa region and too few temper-atures were available for the Amami region, hencetemperature data for those 2 regions are presentedonly in Appendix 1, not in figures. Lacking completedata for year-round temperatures at these depths andlatitudes, no relationships between colony widths andtemperatures can yet be inferred (Fig. 9).

Vertical distribution of each species

Fig. 10 shows collecting depth data arranged in 20 mincrements. All 3 species were collected from nearlythe same depth range, 100 to 320 m. Most samples ofParacorallium japonicum were taken from waters lessthan 261 m deep, with only one colony from 300 mdeep. For P. japonicum, most samples (35 colonies,45%) were taken from the 200 to 220 m depth range,but 13 samples (17%) were collected between 120 and140 m, the shallowest depth range for this species.Colonies of Corallium konojoi were collected fromshallower than 255 m, with most colonies collectedbetween 120 and 140 m. The shallowest sample, 115 mdeep, was recorded for this species. Colonies of C.

273

Colony width (cm)

Co

lony

hei

ght

(cm

)

4020 60 80 100 120 140 160

20

40

60

80

100

95% confidence interval

y = 15.976 + 0.36205xr2 = 0.74569

A

Co

lony

wid

th (c

m)

Diameter of the main stem0 4 8 12 16 20 24

20

40

60

80

100

y = 36.662 + 4.1484xr2 = 0.79103

28

120

140

16095% confidence interval

B

Fig. 6. Corallium elatius. Relationships between (A) colonywidth and height and (B) main stem diameter and colonywidth for collected colonies of C. elatius. Each data pointrepresents measurements taken from a photograph of 1colony. Dotted lines show the 95% confidence interval of the

correlation equation line

0

5

10

15

20

25P. japonicum

C. elatius

C. konojoi

Num

ber

of c

olon

ies

Water temperature (°C)14 16 18 2015 17 19 21 22

Fig. 7. Water temperatures recorded at time of collection for each species

0

5

10

15

20

25

115–120 m (N = 5)

125–130 m (N = 11)

135–140 m (N = 9)

145–150 m (N = 5)

A S Kagoshima

Wat

er te

mpe

ratu

re (°

C)

Month

0

5

10

15

20

25

203–219 m (N=10)

237–261 m (N=4)

296–315 m (N=4)

J F M A M J J A S O N D

B Ishigaki

Fig. 8. Harvest station water temperatures by depth range(A) in the southern Kagoshima region, 30.8° N and (B) in the

Ishigaki region, 24 to 25° N

Mar Ecol Prog Ser 397: 269–278, 2009

elatius were collected from deeper water than theother 2 species, and they were collected evenly fromthroughout their range. Nine colonies (19%) were col-lected from 200 to 220 m, 8 colonies (17%) from 280 to300 m and 8 from the deepest range, 300 to 320 m.

Relationship between latitude and vertical distribution

Samples of Paracorallium japonicum were collectedfrom 120 to 300 m deep. In northern regions they weregenerally collected from shallower depths (115 to 195 m),but in middle and southern regions they were sampled

from deeper depths (194 to 319 m). Colonies of Coralliumelatius were found in deeper water than the other spe-cies. They were collected from 140 to 319 m deep, show-ing a tendency to inhabit shallower depths in higherlatitudes and deeper ones in lower latitudes (Fig. 11).

DISCUSSION

Identification problems

The Coralliidae is renowned for difficulty in identifi-cation to species level. Their taxonomy has not beenstudied in Japan since Kishinouye, over 100 yr ago,and the original specimens he described in his publica-tions are unavailable for comparison; apparently, theyhave been lost. Therefore, our identifications are stilltentative. With more collections and more study, it maybe found that the Ryukyu corals differ substantiallyfrom species in northern Japan, and are new to sci-ence. Meanwhile, reliance on just axis color, which hasbeen traditionally used in Japan to sort commerciallyvaluable samples, has sometimes led to taxonomicmisidentifications. For example, 5 white coral speci-mens were classified by manned submersible and ROVcrews as belonging to the white coral species known asCorallium konojoi. However, examinations of theirsclerites with a microscope showed that 2 specimenswere actually a white variety of C. elatius, one wasParacorallium inutile and 2 were possibly yet-unde-scribed species. Relying on axis color only for identifi-cation of samples of C. elatius, known as the pink coral,may also result in misidentification. This so-called pinkcoral has 2 branching morphologies: one with veryskinny branches that arise abruptly from a stout trunk,and one with tapering branches arising from a more

274

Colony width (cm)

Wat

er t

emp

erat

ure

(°C

)

0 40 60 80 100 140120 16020

5

0

10

15

20

25

P. japonicum

C. elatius

C. konojoi

Dep

th (m

)

Number of colonies

P. japonicum

C. elatius

C. konojoi

5 10 15 20 25 300 35

100

120

140

160

180

200

220

240

260

280

320

300

Fig. 9. Paracorallium japonicum, Corallium elatius and C.konojoi. Relationship between colony width and water

temperature at time and site of collection

Fig. 10. Paracorallium japonicum, Corallium elatius and C.konojoi. Frequency of collection depths for each species, in

20 m depth bins

0

50

100

150

200

250

300

35024 26 28 30 32

Latitude (°N)

Dep

th (m

)

Ishigaki Okinawa Amami S Kagoshima

P. japonicum

C. elatius

C. konojoi

Fig. 11. Paracorallium japonicum, Corallium elatius and C.konojoi. Relationship between latitude and depth of collection

for each species

Nonaka & Muzik: Harvest records of precious corals

slender trunk. Because branching pattern is often animportant character for identification in octocorals, onthe basis of their very different branching patterns the2 morphologies could perhaps be separated into 2 spe-cies. However, the shapes and sizes of the sclerites areindistinguishable, so for the present, both morpholo-gies remain classified together. (Data on current andother factors possibly affecting branching pattern arenot available.) In summary, several identificationsreported in the scientific literature and identificationsused by commercial enterprises are doubtful, andthose in the present study may be corrected in thefuture. It is hoped that DNA studies of preserved andnew material will help to clarify the situation.

Estimates of colony size

Because colonies are often broken during harvest, itwould be helpful for conservation of the resource to es-tablish an equation for the relationships betweencolony height and width, and colony width and mainstem diameter. For example, if the height is known, thewidth before breakage can be calculated. Knowing thisinformation would assist conservation efforts by help-ing to set and enforce collection size limits. Also, whencolony shape is an important character for identifica-tion, taxonomic studies might be served. Unfortunately,with the data from the present study, only the correla-tion analysis for Corallium elatius yielded an equationthat was significant (Fig. 6). Although many samples ofParacorallium japonicum were measured (N = 51),there may be too great a variation in the shape of thisspecies to establish a predictable relationship. For C.konojoi, sample size (N = 11) may have been too small.The relationships between size and age, and especiallyage at reproduction, are very important to know in or-der to guide conservation efforts, but as yet are un-known for any of these species (only large, maturecolonies should be allowed to be collected, if any at all).It should be noted that colonies of P. japonicum wereroutinely the smallest of the 3 species collected.

Colony distribution and width

The maximum colony width recorded for all sampleswas 157 cm for a specimen of Corallium elatius (Fig. 3).Kishinouye (1904a) reported large-sized colonies of C.elatius (up to 100 cm tall and wide) and, indeed, ourdata show that colonies of C. elatius were significantlywider than those of Paracorallium japonicum and C.konojoi (Fig. 3). Our data also show samples of C.elatius tended to be wider at lower latitudes than athigher latitudes (Fig. 5). One explanation for the larger

widths sampled at lower latitudes may be historical,not biological. The fishery of precious corals began inKagoshima in 1902 by dredging (Kitahara 1904), andwas quite intense. As a result, the resources may nothave recovered yet in that area. Harvest began in Oki-nawa much later, in 1959 (Kosuge 1987), but withoutmuch success. In 1972, research on the coral resourcesin the northern Ryukyu Archipelago was begun bycommercial submersible (Kosuge 1987, Suzuki 1999).Since 1979, collection in the Kagoshima and OkinawaPrefectures has been permitted only by ROV and sub-mersible (Suzuki 1999).

Distribution of Japanese species in Japan and thePacific

Three commercially valuable species of JapaneseCoralliidae are known to have been collected in south-ern Japan, Kochi, Kagoshima, the Bonin Islands and theRyukyu Archipelago (Kosuge 1987, Suzuki 1999), butthere are no summary reports of their distribution inJapan. Their northern limit appears to be northernKyushu, off Nagasaki and Goto Island (Kosuge 1987,Suzuki 1999). The northernmost record in Japan forCorallium is a specimen from Sagami Bay (southwestTokyo) which may or may not be Paracorallium japon-icum (Nonaka & Muzik in press). Despite several studies,no Japanese Coralliidae have ever been recorded fromthe Hawaiian or Midway Islands (Bayer 1956, Grigg1974, 1993). In the present study in Japan, colonies of C.konojoi were found mostly in the southern Kagoshimaregion (Fig. 4), suggesting that the Ryukyu Archipelagomay be the southern limit for this species. The other 2species, P. japonicum and C. elatius, were presentthroughout the study area, and therefore it is possiblethey occur at even more southern latitudes. As men-tioned in the ‘Introduction’, according to Grigg (1975),colonies tentatively identified as C. elatius and C. kono-joi were collected in Palau, and in one other unconfirmedreport (Harper 1988), colonies of C. elatius, C. konojoiand P. japonicum were recorded in the South Pacific re-gion. However, because of the difficulties and problemsassociated with identification to species level of thisgroup, and without collected material to examine in or-der to confirm identifications, these records should beviewed with skepticism.

What are the environmental factors of Coralliumdistribution in the Ryukyu Archipelago?

This question cannot yet be answered fully becausetoo few environmental variables have been reported.Regarding vertical distribution, the samples were

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Mar Ecol Prog Ser 397: 269–278, 2009

found at depths of 115 to 319 m (Fig. 10, Appendix 1)and so appear to live at shallower depths than do spe-cies in Hawaii (Corallium secundum at depths of 350 to475 m, Grigg 1993). One of the deepest records forCorallium was an undetermined species collected fromaround Midway at depths of 1000 to 1500 m (Grigg1993).

Although the depth ranges found in the presentstudy are not yet definitive, the data suggest that thesespecies live deeper at lower latitudes (in the Amami,Okinawa and Ishigaki regions) than in higher latitudes(in the southern Kagoshima region) (Fig. 11). Mostcolonies of Paracorallium japonicum were collectedfrom depths of 200 to 220 m, and Corallium konojoiwere collected from depths of 120 to 140 m (Fig. 10).

Grigg (1974) commented that Corallium was foundin areas of strong bottom currents in the North Pacificbasin. Indeed, current is likely to be of extreme impor-tance for determining species distribution of Coral-lium, as well as many other arborescent species in theSubclass Octocorallia. Currents also likely have anunkown effect on colony shape and size, as illustratedby the 2 morphotypes of what at present are stilllumped as pink coral, in the species Corallium elatius.

In summary, the present study is a first step towardsdetermining the precious coral resource in Japan andestablishing its proper management and conservation.Information on precious coral distribution, biomass,taxonomy and biology, especially growth rates, age andsize at fertility and timing of reproduction are needed inorder to determine if there are still sufficient coralsremaining to allow their selective harvest, especiallyof Corallium elatius, in the more southern regions.

Acknowledgements. We thank Dr. N. Iwasaki, Associate Pro-fessor of Kochi University, who provided information aboutprecious corals collected from mainland Japan. Y. Imahara,Researcher of Wakayama Laboratory, Biological Institute onKuroshio, Kuroshio Biological Research Foundation, and F.Iwase, Managing Director of Kuroshio Biological ResearchFoundation, shared much useful knowledge about Coralliumand other octocorals with us. We thank Dr. M. Yamaguchi forproviding us literature about precious coral biology and cul-tural history. E. Neeley of SeaWeb generously shared publi-cations from the SeaWeb coral library with us. We thank thestaff of Okinawa Churaumi Aquarium, especially H.Yamamoto who gave us advice on data analysis, Y. Kanayaand Dr. S. Kai who helped us analyze the data and A. Shinjowho made measurements from photos for this study. Specialthanks to Dr. S. Uchida, director of Okinawa ChuraumiAquarium, for management of this research.

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Nonaka & Muzik: Harvest records of precious corals 277

Date Sampling Latitude Method Depth Temperature Sample(dd/mm/yy) area (°N) (m) (°C) no.

04/06/2005 Okinoerabu Is. 27.40 Manned sub 250–270 16 3 06/06/2005 Iou Is. 30.80 Manned sub 125–140 14–15 4 08/06/2005 Iou Is. 30.80 Manned sub 138 15 1 12/06/2005 Kikai Is. 28.20 Manned sub 195 19 1 13/06/2005 Kikai Is. 28.20 Manned sub 212–215 19 1 18/06/2005 Iou Is. 30.80 Manned sub 120–130 17–18 3 19/06/2005 Take Is. 30.80 Manned sub 130 17 1 20/06/2005 Iou Is. 30.80 Manned sub 145–160 16–17 2 15/08/2005 Kita Chohozone 25.30 ROV 312–316 17 2 18/08/2005 Yaebise 25.00 ROV 239 19 119/08/2005 Minna Is. 24.75 ROV 315 17 1 21/08/2005 Tarama Is. 24.60 ROV 282 17 1 24/08/2005 Ishigaki Is. 24.40 ROV 290 16 1 28/08/2005 Ishigaki Is. 24.40 ROV 272 16 2 29/08/2005 Hatoma Is. 25.00 ROV 219 17 1 20/09/2005 Izena Is. 27.00 ROV 202 20 1 26/11/2005 Ishigaki Is. 24.40 ROV 290 16 1 28/11/2005 Tarama Is. 24.60 ROV 205–232 18 4 19/12/2005 Izena Is. 27.00 ROV 200–206 17–20 12 20/12/2005 Izena Is. 27.00 ROV 201–214 19–20 10 23/12/2005 Ishigaki Is. 24.40 ROV 303 17 1 26/12/2005 Tanega Is. 30.50 Manned sub 160–175 17 2 09/01/2006 Izena Is. 27.00 ROV 194–197 20–21 3 10/01/2006 Izena Is. 27.00 ROV 194–197 20–21 1 11/01/2006 Okinawa Is. 26.50 ROV 215–221 19 2 15/01/2006 Ishigaki Is. 24.40 ROV 307 15 1 19/01/2006 Tarama Is. 24.60 ROV 278 17 1 20/01/2006 Tarama Is. 24.60 ROV 277 14 1 10/02/2006 Tanega Is. 30.50 Manned sub 190–200 16 3 11/02/2006 Tanega Is. 30.50 Manned sub 150 17 1 12/02/2006 Tanega Is. 30.50 Manned sub 145 17 1 13/02/2006 Tanega Is. 30.50 Manned sub 220 17 2 14/02/2006 Tanega Is. 30.50 Manned sub 165–220 16–17 2 21/02/2006 Mage Is. 30.80 Manned sub 120–125 18 2 22/02/2006 Mage Is. 30.80 Manned sub 130–135 18 3 25/02/2006 Iou Is. 30.80 Manned sub 155 18 1 27/02/2006 Iou Is. 30.80 Manned sub 130–135 16–18 2 27/02/2006 Kuchierabu Is. 30.40 Manned sub 145 17 123/06/2007 Ishigaki Is. 24.40 ROV 319 16 105/07/2007 Ishigaki Is. 24.40 ROV 317 15 1 16/08/2007 Ishigaki Is. 24.40 ROV 249 19 2 22/08/2007 Yaku Is. 30.30 Manned sub 170 17 2 30/08/2007 Amami Is. 28.30 Manned sub 295–300 18 2 02/09/2007 Nakanougan Is. 24.20 ROV 219 18 1 04/09/2007 Tanega Is. 30.80 Manned sub 145 17 1 05/09/2007 Hateruma Is. 24.00 ROV 296 16 1 06/09/2007 Kakeroma Is. 28.10 Manned sub 250 20 1 08/09/2007 Kikai Is. 28.20 Manned sub 195 22 1 12/09/2007 Ishigaki Is. 24.40 ROV 228 18 1 21/09/2007 Iou Is. 30.80 Manned sub 150 18 1 23/09/2007 Takeshima Is. 30.80 Manned sub 140 17 1 22/10/2007 Tanega Is. 30.50 Manned sub 205 17 2 23/10/2007 Amami Is. 28.30 Manned sub 260 17 1 29/10/2007 Tokuno Is. 27.80 Manned sub 285 17 1 06/11/2007 Iou Is. 26.70 ROV 209 18 1 08/11/2007 Yuse 30.80 Manned sub 120 20 1 13/11/2007 Iou Is. 30.80 Manned sub 130 17 1 02/12/2007 Tarama Is. 24.60 ROV 203–216 19 2

Appendix 1. Precious coral harvest data in the Ryukyu Archipelago from 2005 to 2008. Is.: Island; Manned sub: mannedsubmersible; ROV: remotely operated vehicle. Substratum was hard rock in all cases

Mar Ecol Prog Ser 397: 269–278, 2009278

Submitted: February 27, 2009; Accepted: November 2, 2009 Proofs received from author(s): December 15, 2009

Date Sampling Latitude Method Depth Temperature Sample(dd/mm/yy) area (°N) (m) (°C) no.

05/12/2007 Tanega Is. 30.50 Manned sub 175 19 3 09/12/2007 Iou Is. 30.80 Manned sub 135 19 1 10/12/2007 Tarama Is. 24.40 ROV 251–261 19–20 2 11/12/2007 Iou Is. 30.80 Manned sub 135 19 1 18/12/2007 Iou Is. 30.80 Manned sub 115 20 1 06/01/2008 Take Is. 30.80 Manned sub 130 18 1 06/01/2008 Ie Is. 26.70 ROV 261 17 1 08/01/2008 Yaku Is. 30.30 Manned sub 205 15 1 08/01/2008 Okinawa Is. 26.90 ROV 303 17 1 9/01/2008 Izena Is. 27.00 ROV 230 18 1 05/02/2008 Take Is. 30.80 Manned sub 120 17 1 07/03/2008 Tarama Is. 24.60 ROV 210–214 20 2 07/03/2008 Yaebise 25.00 ROV 220 20 1 09/03/2008 Hateruma Is. 24.00 ROV 298 18 1 16/03/2008 Nakanougan Is. 24.20 ROV 203–207 19 2 25/03/2008 Hateruma Is. 24.00 ROV 297 17 1 29/03/2008 Hatoma Is. 25.00 ROV 219 19 1 04/04/2008 Yaebise 25.00 ROV 237 19 1 05/04/2008 housanzone 25.30 ROV 228 20 1 13/04/2008 Nakanougan Is. 24.20 ROV 212 18 1 14/04/2008 Nakanougan Is. 24.20 ROV 232 18 1 05/05/2008 Nakanougan Is. 24.20 ROV 213 19 1 18/05/2008 Iou Is. 30.80 Manned sub 130 16 2 21/05/2008 Iou Is. 30.80 Manned sub 145–150 16 2 22/05/2008 Ishigaki Is. 24.40 ROV 248 20 1 22/05/2008 Yaebise 24.90 ROV 216–225 21 2 27/05/2008 Housanzone 25.30 ROV 226 20 1

Total 143

Appendix 1. (continued)